This invention relates generally to adjustable, flexible strap suspension systems used in hard hat shells.
More specifically, this invention relates to means for adjusting the width of such a suspension system to fit heads of varying size without causing the vertical centerline of the system to shift away from the vertical centerline of the shell. Adjustable head band suspension systems for use in hard hat shells have, generally speaking, long been known in the prior art. U.S. Pat. No. 3,555,560 issued to H. A. Raske on Jan. 19, 1971 discloses one of many such examples. The reference system employs two diagonally extending crown straps which cross one another over the top of the wearer's head and connect on rear end portions thereof to two tabs located on rear end portions of a head encircling head strap. Forward end portions of the diagonally extending crown straps connect to two tabs formed on a brow pad at the front of the system. Forward end portions of the head strap contain a series of pin holes, any one of which can be selected for engagement with pins located on opposite side end portions of the brow pad.
The Rascke system presents two difficulties typically encountered in head band systems of the prior art. First, adjustments of the head encircling strap to fit heads of varying size must be made near the forward ends of the head strap on opposite side end portions of the brow pad where the spacing between the head strap and brim of the hard hat shell is quite narrow. Second, care must always be taken to always make equal adjustments in both ends of the head strap in order to maintain the suspension system centered in the shell.
U.S. Pat. No. 3,500,474 issued to H. W. Austin on Mar. 17, 1970 discloses one of many prior art safety hat suspension systems which are adjustable at the rear of the shell. The reference system employs a head encircling head strap having overlapping rear end portions which are adjustable directly between two points of attachment of the head strap to a rear end portion of the shell. As such, the reference system avoids the first mentioned difficulty encountered in the Rascke system, but introduces another problem in that adjustments of the head strap can only be made directly between the two attachment points of the strap on the rear end portion of the shell. The much longer remaining portion of the strap extending from the two rear attachment points along the sides and around the front of the head are substantially unaffected by such rear end adjustments. As a result, when using the Austin type system, the adjustments for smaller size heads will cause the head to become decentered and shift toward the front of the shell, while adjustments for larger sized heads will cause the head to decenter and shift toward the rear of the shell. Also, when the rear end portions of the head strap of Austin are sufficiently loosened between the rear shell attachment points in order to fit larger sized heads, the shell can become floppy and unstable on the head of the wearer.
Accordingly, by means of the present invention, these and other problems encountered with prior art safety hat suspension systems are substantially reduced if not altogether eliminated.